1. Field of the Invention
The present invention relates to a method of desorbing a granular carbonaceous adsorption agent that is loaded with noxious materials or other harmful substances, and in particular relates to a method of desorbing activated coke that is loaded with sulfur oxides and/or nitrogen oxides from flue gases. The present invention also relates to an apparatus for carrying out such a method.
2. Description of the Prior Art
A method is known from a German research report of the Federal Ministry for Research and Technology (BMFT-FB-T-81-147) according to which a tubular desorber is used for regenerating activated coke that was loaded with noxious materials in a flue gas desulfurization plant. In the desorber, the activated coke is regenerated by being heated to temperatures of between 305.degree.-500.degree. C. In this connection, the desorber acts as a gas-solid heat exchanger, since the heat of a hot gas that enters the heat exchanger is transmitted via the walls of the tubes to the solid coke that flows through the tubes. Since the heat transfer is effected through the walls of the tubes, the temperatures of the hot gas and of the tube walls must be significantly greater than the desorption temperature. Since the tubes are exposed to the corrosive desorbed gases, it is necessary at the required high temperatures to impose high requirements for the material used for the tubular absorber, at least in the preliminary heating zone of the desorber. In a high temperature zone that follows the preliminary heating zone, rich gas is recirculated through a free fill in order to heat the activated coke to the required temperature. From the fill, the activated coke is introduced into tubes where it is subjected to a cooling that is effected by air via indirect cooling of the activated coke that flows in the tubes.
An object of the present invention is to provide a method according to which, during heating of the adsorption agent, lesser requirements are imposed for the materials used in the heating zone for guiding the adsorption agent.